Adrenoleukodystrophy (ALD) is a progressive neurodegenerative condition caused by a mutation in the ABCD1 gene that is located on the X-chromosome. The mutation results in the build-up of a substance called very long-chain fatty acids (VLCFAs), which affects the nervous system and the adrenal glands.

The diagnosis of ALD can be quite difficult, because its behavioral symptoms closely match those of other conditions, like attention-deficit/hyperactivity disorder (ADHD). Therefore, ALD must be considered as a possibility in:

• young boys with ADHD showing other neurological symptoms, and those who do not respond to ADHD medication
• young men experience increased difficulty in walking and a progressive loss of motor coordination

In men with adrenocortical insufficiency (Addison’s disease), physicians should test for ALD as a possible cause even if other disease symptoms are absent.

Early diagnosis of ALD is crucial because the limited treatment options available only work in the very initial stages of the disease. A blood test is the most common diagnostic test used for ALD. Others primarily serve as confirmatory tests, determine ALD progression, or help in screening.

Tests for initial diagnosis

Blood tests

Elevated levels of VLCFAs in the blood and other tissues, such as the skin, is a characteristic of ALD. A blood test can help determine the concentration of these fatty acids. Measuring the levels of adrenal hormones in the blood can also help determine adrenal gland dysfunction, another characteristic of the disease.

Skin biopsy

A skin biopsy, where a small sample of the patient’s skin is taken and examined in the lab, can also help doctors check for increased concentration of VLCFAs to diagnose ALD.

Magnetic resonance imaging (MRI)

MRI is a noninvasive technique that uses magnets and radio waves to image organs. Brain MRIs can capture the nerve damage in the patient’s brain and reflect brain abnormalities indicating ALD, like damage to the myelin sheath.

Genetic testing

Mutations in the ABCD1 gene can be identified using genetic testing. This is primarily used to confirm the diagnosis, provide genetic counseling to the family, and in future prenatal counseling. Other family members who may be carriers but not showing ALD symptoms — such as siblings — can be identified through genetic testing giving an opportunity to start with treatment early.

Tests to monitor disease progression

Eye tests

ALD can cause cysts on the optic tract (an extension of the optic nerve) that affect vision. Periodic vision response checks can help in monitoring disease progression.

MRIs

MRIs can also help determine how the disease is progressing. Even in the absence of neurological symptoms, brain MRIs can reveal abnormalities showing the breakdown of the protective sheath (myelin) covering the nerves.

Newborn screening

The goal of newborn screening is to identify serious conditions that, undetected and untreated, may be fatal or cause life-long disability. The U.S. Department of Health and Human Services added ALD to their recommended uniform newborn screening panel in 2016, although its inclusion is at the discretion of each state. A current list of states conducting screening can be found here.

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